I am a 17 year old, i don't smake and i am very active in sports and in good health. A couple of weeks ago, maybe even before that i started spitting up blood in the mornings only. I noticed that the first couple of spits were very full of blood but then it would go away after a couple of spits. This happens almost every morning. I don't ever get chest pains and i don't ever cough alot other then when i have a cold which isnt very often. I don't know if this is related to my chest or maybe my lungs but i was just wondering if this could be a serious problem or not.

If this continues it is probably a good idea to have this evaluated by your doctor. Most commonly, blood in the saliva is actually from a slight nose bleed. It may be that you have a very slight nose bleed that is draining backwards with the blood pooling at night so that you are noticing it most in the morning.

Keeping the air moist can help prevent nose bleeds. This can be done by using a humidifier or even a nasal moisturizing gel (or spray although the gels work better in my experience).

There are other less common causes so if it isn't getting better your doctor can help determine if other testing is needed.